Compressor unloading means



March 23, 1954 O A L US AL COMPRESSOR UNLOADING MEANS Filed Nov. 14,1949 4 Sheets-Sheet l INVENTORS arm A. LABUS F l .EMJL z: NEUBAUER q' ByROBERT a. MINER ATTORNEYS March 23, 1954 o. A. LAIBUS ETAL 2,673,025COMPRESSOR UNLOADING MEANS Filed Nov. 14, 1949 4 Sheets-Sheet 2 IN VENTORS 01'1'0 A. LABUS EMIL T. NEUBAUER By ROBERT c. MINER ATTORNEYS March1954 o. A. LABUS ETAL- COMPRESSOR UNLOADING MEANS 4 Sheets-Sheet 5 FiledNov. 14, 1949 120512121 0. MINER ATTORNEYS March 23, 1954 o. A. LABUSETAL 2,673,025

COMPRESSOR UNLOADING MEANS Filed NOV. 14, 1949 4 Sheets-Sheet 4INVENTORS OTTO A. LAB

US EMIL T. UBAlER y ROBERT MINE ATTORNEYS Patented Mar. 23, 1954 7COMPRE SS R-UNLOA=DIN GuMEAN S OttouimLh-busyEin-il T Neubauer;andRoliert G2 Miner L'aaCrosse, Wis, assignors -to The-TrancCbmpanygzLazGTossc; Wis.

Application N avemlierl l, 1949; Serial No.1127,01;6

This; invention relates in to' compressors" and. to the. control ofcompressors: in reffigemtiontemsio f'fth'etype, having a compressor; acondem ser andfan evaporator: An .objectofthe-present invention is toprovide'a compressor which may hetconti'olled-otto operate atits'maximumcapacity: or: at. one of several? fractional amounts of its. maximumcapacity without" any, substantial changeinzspeedi Another objectoff'thig invention is." to: provide 1 U a compressor iniwhich'" the:unloading "mechanism and? its" control are: energized'iby" thelubrication systemofthecompressor."

Ai third otij'ect 'of. ourinvention-is to provide-a compressorincludingunloading; means therefor 1 5which-isfincxpensive:to-manufacture and easy to assembleimd repair:

A- furtherobiectofour inventiomis to providemeansto controlthefoperationzof the-compressoraccordiizg-tor conditions'of,t-he:refrigeration-sys= 2U tem ofwiiich' it is'a part1 Stillanother-object of the-invention is toprovideacompressor'unloadingmechanismwhicli is" responsive to the starting mechanism of themotornvhich'drivesthe'compressorr Otherobjects-and-'advantages of theinvention-'- will be-clearl'y apparentas'tlie specification mmceeds't'o" describe the" invention with refrencetotheaccompanying-"di'awings in Whicli--- Fig". l' is-a' seetionalview-,more ordess' diagram matic; of the apparatus of this invention. 3

Fig: 2%is a= cross-'sectional view of a cylinder" showing =a modifiatiorr of: my" invention.

Fig-L Wi a sectional 'vi'ew takenon tiieline-3- ofi'Fig. J

Fig;- e is' a top pl-an vevw of thecylinderlihezvoi the form of tlieirrventioirshown-in Fig: 1.

Fig: 5 is artop plan view 'of cylineler: liner 1 and valveliftingsleeve-*of-tlie form of= the inventioni of Figm? Fig; 6 Y alside view ofthe valvalifting sleeve? of' the form of the-invention sliowmin- FigrZE.

Visa-diagrammatic view ofl'th'e compres sorsmotor wiring anmthecompressor 'oilrpipingc 8:; is: a sectional. view: tazkem om an plane:through; the: axes: of: the: cylinders thee comepresent;

Referrineqznomto Eige'.l;..numeral; l Osdesignates thezhodyorr-blockrofa theacompressor inzwhich is: rotatarbiy mountech, a:crankshaft: 12: which: isz: drivenzbyiramelectrieimotor on aminternalcomebustiom engine: or other. suitable: nowerr meansz- Thezcomprcssorrmarm'haveaany desired mnnberzofi cylinders; amiiany desiredarrangementzoftcylins 31Glaiins; (Cl. 230"2T old andTwelIIknoWnandidonctconstitute part'ofi' this invention. For,purposes.offillustration and description itfwilllb'e; assumedlthatlthecompres sor'has four cylinders.

Connectingrods M'are rotatably connectediat' one'endito thecranksliaft'l2 and they are pivotally; connectediat' the other end to each. ofithexpistons l6? Each cylinder com-prises acyIinder, liner 5 8 which isinsertedifrom the" outer end.of' the: cylinder before the; valve plate2B" and the; cylinder head 22" have been" mounted in place;Thecylind'erliner is supportedat'itsouter endbw theouterrwa'll"2ilofftlieicylinder and at'its inner end" by the wall 262 ofthe suction manifold 23" which communicates with the associated refrig=crating system througlia suctionline-30 whicliis" shown"diagrammatically. Thegsuction manifold 28. also communicates withthecrankcase. 32- throughaipluraiity of check valves 34; Whenthercompressor is'startedthe'pressure'in'theisuction-manifold-'dro.p-srapidly andthe differenceiinpressureabetween: the" crankcase 32 and thesuc tion: manifold:- 28closes the clieck'rvalve" 34'? and prevents asudden"dropin'pressure-imtlie crank case which*wouldba'usetheoil tofoam-excessive= 1yand--form, a" large volume? of foam. Dueto' leakagenf"gasffrom-thercrankcase '32to"th'e suc' tion manifold 28? thepressures'dni these" spaces. soon become substantially equal; and-thecheck valvetopens'to allow'any oil.accumulationimtl'ie" Osuctionima'nifold to drainback into: the crankcase:

'Ilre-cy-linder liner l 8 has a" plurality of-suctiom valve 'ports"36annularly spaced-around its wall; When' the*piston' Hi descends and thesuction valve '3Bopens; as 'flows fromthe suction mani--- fold throug-hports flfi into tliecylinder: The suc tion valve: 38 i -urged toward itsseat by a phr rality" of coil spring-s10 whichare located in pocketsinthe'valve mate-2w. When the piston-" I 6' ascends; the dischargevalve- 42 opensagainst the action-of springs l' l positioneel in 'adischarge valve-= cage= 4451* A dischargevalveseat 48 is secured to'-the discharge valve cage 4-6=by a nut*50 Tlie discl'iarge-ga's from'thecliambers 52 of' thc heads fl is manifolded to a sing-ldisc-liargediiie54*w-hicli isshoww diagrammaticallyo Eine 54 isconnected' to acondenser-53 whicli'in'turnis=con=- nectedto a;- liquid -receiver =58:Liquid from: the"- reeeiver fiowatliroughan expansion valvetfl toeheatexchangewfi 22 Tliemattento-be cooled snc-li" asgadrzor waterrflowsthrough conduitifilin the die IGGfiOIITShQWII Joyrthe arrow Imordem toonnratezthe compressonattsubstane tiaili -'cons;tant; speed; but att.incrementszofl. its full capacity, we have provided means for holdingone or more suction valves in open position to render the cylindersserved by said valves inoperative in compressing gas.

Referring to Fig. l and Fig. 4, the cylinder liner I 8 has a pluralityof holes 66 which support pins 68 for sliding movement. Springs 10 actagainst heads on the pins 68 to urge the pins downwardly away from thevalve 38. A cylinder seal ring 12 is held against upward movement withrespect to cylinder liner I8 by a snap ring 14 which engages in a groovein the cylinder liner I8. A cylinder member 16 is supported on theoutside of cylinder liner I8, and it is further supported at its end bythe lower wall 26 of suction manifold 28. The cylinder member 16 has aplurality of spring pockets which receive a plurality of springs 18which act against a piston 80. The piston 80 supports a fiat ring 82which in turn supports the pins 68. Cylinder 16 has a hole 84 throughwhich oil under pressure will flow from fitting 86 when the cylinder isto be loaded. A cylinder is loaded by allowing the suction valve tooperate so that the cylinder compresses gas. The oil flows from hole 84through recess 88 in the wall of cylinder liner I8. From recess 88 theoil flows through holes 96 in cylinder 16 into the oil cylinder spaceand moves piston 80 downwardly against the action of springs 18.Downward movement of piston 80' allows springs 10 to move pins 68 andring 82 down. When pins 68 move down they allow suction valve 38 to openand close in its normal manner and the cylinder is operating to compressgas or is what is commonly called loaded. Cylinder seal ring 12,cylinder 16 and piston 80 may all be provided with O-rings as shown.Said O-rings are of some flexible material such as rubber and preventleakage of oil between the parts.

The operation of the control mechanism will now be described. Areservoir of oil 92 is contained in the bottom of the crankcase 32. Theoil from reservoir 92 is used to lubricate the compressor and operatethe unloading mechanism. An oil pump shown diagrammatically at 94 has aninlet pipe 96 extending down into the oil reservoir. It should beunderstood that the oil pump 94 may be driven in any suitable manner.

For instance it may be located at the end ofthe crankshaft and connectedto be driven by the crankshaft. This is an old and well known Fexpedient. The oil flows from pump 94 to a check valve 98 whichmaintains a constant pressure in the oil system and returns the excessoil to the reservoir through pipe I00. valve 98 the oil under pressureflows through a pipe I02. Pipe I02 has a branch pipe I04-oonnectedthereto. Branch pipe I04 supplies lubricating oil to various parts ofthe compressor such as the shaft seal and the bearings. The oil flowsfrom pipe I02 to a solenoid operated valve I06 the operation of whichwill be described later. A pipe I08 conducts oil from the solenoid valveI06 to a valve body I09 of a valve indicated generally by numeral H0.The valve IIO is secured to the block I of the compressor and extendsinto the crankcase 32. The pipe I08 has a branch pipe I I2 whichconducts oil to the unloading cylinder 16 of one of the compressorcylinders which is therefore always loaded whenever the solenoid valveI06 is open. The other three cylinders are loaded or unloaded accordingto the refrigerant requirements of the system as will presently bedescribed. The pipe I08 is connected to passageway H4 in the valve bodyI09. Passageway I I4 connects with valve bore I I6 in the valve bodyFrom check.

I09. A plunger II8 has a. sliding fluid tight fit in bore H6. PlungerII8 has a small hole I20 drilled in one end for the passage of oilthrough the hollow center of nut I22. Nut I22 has a nozzle I24 fromwhich the oil flows in varying amounts according to the positoin ofscrew I26 which is in threaded engagement with arm I28. The operation ofarm I28 will be described later in the specification. It may thus beseen that a small quantity of oil is allowed to escape from bore II6through hole I20, nut I22 and nozzle I24. The rate of escape of oildetermines the pressure in bore I I6 tending to force plunger II8 to theleft in Fig. 1. A spring I30 is supported on stud I32 which is inthreaded engagement with the valve body I09 and urges plunger II8 to theright in Fig. 1 against the oil pressure tending to urge plunger I I8 tothe left. The bore I I6 of the valve body I09 has three grooves I34,I36, and I38, As plunger H3 moves to the left in Fig. 1 grooves I34, I36and I38 are successively connected with the oil pressure in bore Il6.Grooves I34, I36, and I38 are connected with pipes I40, I42, and I44respectively. Pipe I40 is connected to one of the unloader cylinders 16as shown in Fig. 1. In like manner pipes I42 and I44 are connected tothe unloader cylinders 16 of other cylinders of the compressor. A pipe146 is connected with the valve bore I I6 to provide for the return ofoil to the crankcase 32.

The valve body I89 contains a bellows I48 which controls the position ofplunger II8 as will now be described. The bellows I48 is clamped to thevalve body I09 by a plug I50 which is in threaded engagement with thevalve body I09. Inside the bellows is a spring I52 which bears at oneend against an abutment I54 which is soldered or brazed to the end ofthe bellows I48. At its other end the spring bears against an abutmentI56 which in turn is held against the spring by a screw I58 threadedinto cover I60 of valve IIO. A cover I62 is threaded on a boss of coverI60 to provide a seal for screw I58. The chamber I64 in which thebellows I48 is mounted is connected by a passageway I66 to the suctionmanifold 28 of the compressor whereby the pressure on the outside of thebellows is substantially suction pressure. The interior of the bellowsI48 is connected by a passageway I68 and a pipe I10 to a pneumatictemperature controller I12 which is connected to a source of air underpressure I14. A thermostatic bulb I15 is supported in the conduit 64 inthe path of the matter leaving the heat exchanger 62. The thermostatic nbulb I 15 is connected by tube I16 to pneumatic temperature controllerI12. The pneumatic temperature controller I12 is a standard device wellknown to those skilled in the art, and since it forms no part of theinvention per se, its construction will not be described in detail. Apin I11 is slidably mounted in valve body I09 and is engaged at one endby abutment I54 of bellows I48. The other end of pin I11 engages arm I28which is pivoted to bracket I18 by pin I which extends through thebracket I18 and the arm I28. Bracket I18 is fastened to the valve bodyI09 in any suitable manner. The bracket I18 and the arm I28 havea'plurality of holes for receiving the pin I80 to provide for moving thepivotal point of arm I28 by shifting the pin I80 to a different set ofholes. A member I82 is secured to bracket I18 in any suitable manner asby spot welding and supports a spring I84 which at its other end pressesagainst the arm I28. Referring 'to Figure 3, the plunger 8 has crowns:

5 iourrrouha bottomed grooves l ss which-are enraged my halls 488 whichin turn are urged to seat in thegrooves l 86' :by the-s rings 1st whichare held 'in place by screws L92 which are in threaded engagement withthe valve body its. Balls 8 by engagingin grooves "I86 insure thatlunger H8 will move in "definite steps to compIetelynneoi/er orcompietelyclose each or the grooves 134, "136-, and 138 to oil pressure.Eig's; 2; 5, and 6'='sliow a'modifie'd form o'f'the hydraulic valveliftih'g meolia'nis'ln. In this form orthe'invention-a' piston [94in theform of cylindrical shell surrounds the cylinder liner l8 and is 'm'outed for slidin'g movement thereon. Piston 1 94 has at i one end aplurality of fingers 196 whichextend upwardly through the suction valveports fl -to engage the suction valve -38 and hold it open duringpertain conditions of Operation 6! the'compre'ssoras w'illbe described.Arubber O- lih'g 198 is supportedon a flange 2-00 of the piston I94 andprevents leakage of=oil around tlie pistor'i. -A-ring2-02 closestheendof'the cylihdera riibber o-ring 204 prevents leakage aroundthering 2 02. Therin'g Z'D'Z isheld against upward movement by a springsnap ring 296 which by its resiliency engages in *a groove 293 inthewall 2-6 ofthesuction manifold-28. The snap rlng fllfihas two ears 2l which are 'pressed toward "each other to mountthe snap ring 2% inthe-groove 208--or'to*remove it therefrom. A spacer *ri'ng "2 l2 channel"shaped in cross-section is mounted =between the' O-rings 1'98 and 294to prevent- -the 'o rings I 98 and 204 from moving to a position atwhich 'theywould close the oil supply-openingfll. Springs 2ft aresupported :7:

in -"noles wali fliand act against theflange 21m to urge-the pistoniMupwardly against the valve 38. When the control mechanism admits oilunder pressure 'to pi'pe 'l"' l0,-the' oil 'flows through openlng flland 'forces-O-rin'g [9t and piston 9t dowhwardlyto allow thesuction'yalve 38 to operate its normal manner.

F igfil is adieigrammatic view showing the Wiring of the compressor"motor starter and the oilpipingoftheeompressor. For the purpose ofexplanation will be assumed thatthe compressor is driven by *ajthreephase motor 2ft having atwo step primary resistance reduced voltagestar'te'r. A conventional motor starter is show'nhaving threeresistors22c bridged by a three pole contactor having contacts 222. Thiscontaetor anauxiliary contact 224whi'ch is'in series with-" thes'ol'enoid valve-106. additional threepole contactor havingcontacts 226is conneeted to supply current from-the supply lines 228 tothe resistors220. The-contacts 226'have anoperating coil notshown and the contacts222 and-224 also have an operating coil not shown. Conventionalauxiliary circuits provide the sequence of operation "by whichcontacts'2'26 are first closed, and-after the motor has started,contacts 222 and 224 are closed. I

Whenthe compressormot'or 2 I8 is started -the don'tacts' 228 "close "and"current "flows from the supply lines through the resistors 22a to themotor 2l8. During this period, contacts 222 and 224 are open and nocurrent is supplied to the solenoid valve I06 and solenoid valve I06 istherefore closed. With solenoid valve [06 closed oil pressure does notreach any of the unloading cylinders 16 and the compressor is completelyunloaded. As the timing device in the auxiliary circuits completes itscycle, the contacts 222 and 224 close, short circuiting the resistors220 and supplying motor 218 with current directly from 6 the :lines 228. When icontact nillicl'osea'ithe -ia'ifi cuit to solenoid valve :l06"is:icomp1eted and isole noid valve 106 opens allowing oil to reachiline H2 and valve M0 to loadi all ofithe compressor cylinders.

I Modus'operandi Having thus described the details of construction ofthe apparatus, the'manner of operation will now be described:

When the compressor motor starting contacts 225 are closed,fthe"solenoidvalve W6 isnotenergized andlines HJBan'di l2 do not receive any oil.Noneiof .the valve lifting cylinders 16 is receiving oil. Consequentlythe springs "18 acting'through pistoneil, rings 82 and pins 68 "areholding the suction valves 38 'ofall cylinders in open position. Whenthe motor starter completes its cycle, solenoid valve iii-5 is energizedand oil pressure reaches lines 1% and H2. "Since the suction pressureinmanifold28 ishigh dur-. ing starting, the bellows MBIis compressed andscrew 12% closes opening in .nozzle I2 3 'to raise the pressurein'valvejboreji l5 an'dflmove plunger M8 to itsextremepposition'totheleftas viewed it in Fig. 1. Wl'thth' plunger us in this positiooil'fiows from pipe J08 through passageway "Hi l and into grooves13$,I'3fi and I38 and then'into pipes Hi0, I'42'andi4. Since thepipes'HZ. 8%, M2, and HM are each connectedtooneof the fluid cylinders16 serving each o'fthelcompressing cylinders E8, the pistonsiill of thecylinders are all forced downwardly by oil pressure, and the springs 10force the, pins 5'3 downwardly so that the suction valves to are allowedto operate in 'theirnorm'al manner so thatall the cylinders areloadeda'ndthe -compressor is operating at its full capacity. After thecompressor has been operating fora period'of time, the refrigerationsystem served by the comprese sor becomes cooled to the designtemperature an'd'the suctionpressuretends to falllbelow the designpressure; drops below 'apredetermined point which may be set as desired"by adjusting screw 158, the bellows Mil expands and acts through pin151"! and arm 828 to move screw I26 away from" nozzle i2 3 allow asufficient amount of foil to -pass through nozzle !2'4"to reduce thepressure in bore =5 l etc the point atwhicnspring -i3ilmoves plunger 1iii to close groove "I33 from oilpressure'an'd'open pipe Hid to thedrain 1'46. The cylinder "served by pipe HM therefore becomesunloadedjbecause springs '18'acting through piston 8i}; ring"8 '2,andpins 68 holds thesuction valve 49 open. If the capacity'oithe threeloaded cylinders is greater thanthe'load'on the refrigeration system,the tendency of the suction pressure to drop will continue, andthebellows i lil'will expand 'iurther'until pipe MZ'is cut on; rro'm'theoil pressure and'connectedto the drain pipe 'ie'ii. Two of the fourcylinders have "thus been unloaded. If the capacity or thetwoloade'dWhen :the suction pressure matic -temperature controller I12 to operatein a manner which will now be described. By Way of example let us assumethat the unloading control is set to maintain a suction pressure notlower than 40 pounds per square inch. The pneumatic temperaturecontroller I12 will vary the suction pressure above or below 40 poundsper square inch as the temperature of the matter leaving coil 62 fallsbelow or rises above a desired temperature.

Let us assume that the bulb I15 is subjected to a temperature above thatwhich is desired. The pneumatic temperature controller I12 will reducethe pressure in pipe I and will therefore reduce the pressure insidebellows I48. With a reduced pressure inside bellows I48 the suctionpressure must drop below 40 pounds per square inch to unload thecompressor. Therefore a suction pressure below 40 pounds per square inchis maintained and the lower suction pressure causes the coil 62 to domore work and to bring the temperature of the matter leaving coil 62down to the desired temperature.

Although we have described in detail the preferred embodiments of ourinvention, we contemplate that many changes may be made withoutdeparting from the scope or spirit of our invention, and we desire to belimited only by the claims.

We claim;

1. A compressor comprising a plurality of compressing cylinders, acommon suction chamber and a common compression chamber, each of saidcompressing cylinders having associated therewith a suction valvethrough which gaseous medium may be admitted from said suction chamherand a discharge valve through which compressed gaseous medium may bedischarged into said compression chamber, and spring means to force thesuction valve to open position, fluid pressure means for overcoming saidspring means, said fluid pressure means comprising an annular pistonslidably mounted on the outer surface of said compressing cylinder influid sealing relationship therewith and providing an an nular fluidchamber between said annular piston and the outer surface of saidcompressing cylinder, fluid pressure creating means, means comprising avalve for conducting said fluid pressure from said fluid pressurecreating means to said annular fluid chamber, and means responsive tothe pressure in said suction chamber for controlling said fluid pressureconducting valve to cut off the supply of fluid pressure to said annularfluid chamber.

2. A compressor comprising a plurality of compressing cylinders, acommon suction chamber and a common compression chamber, each of said.compressing cylinders having associated therewith a suction valvethrough which the gaseous medium may be admitted from said suctionchamber and a discharge valve through which compressed gaseous mediummay be discharged into said compression chamber, means comprising anannular piston slidably mounted on the outer surface of said compressingcylinder in fluid sealing relationship therewith and providing anannular fluid chamber between said annular piston and the outer surfaceof said compressing cylinder, valve engaging means supported by saidannular piston, spring means acting against said annular piston andtending to move said annular piston and said valve engaging means towardsaid suction valve to force said suction valve to open position, fluidpressure creating means, means comprising a valve for conducting thefluid pressure from said fluid pressure creating means to said annularfluid chamber to force the annular piston in a direction away from saidsuction valve against the force of said spring means and meansresponsive to the pressure in said suction chamber for controlling saidfluid pressure conducting valve to cut off the supply of fluid pressureto said annular fluid chamber.

3. A compressor comprising a plurality of compressing cylinders, acommon suction chamber, and a common compression chamber, each of saidcompressing cylinders having associated therewith a suction valvethrough which gaseous medium may be admitted from said suction chamherand a discharge valve through which compressed gaseous medium may bedischarged into said compression chamber, and spring means to force thesuction valve to open position, fluid pressure means for overcoming saidspring means, said fluid pressure means comprising an annular pistonslidably mounted on the outer surface or said compressing cylinder influid sealing relationship therewith and providing an annular fluidchamber between said annularpiston and the outer surface of saidcompressing cylinder, fluid pressure creating means, means comprising avalve for conducting said fluid pressure from said fluid pressurecreating means to said annular fluid chamber, fluid means for movingsaid fluid pressure conducting valve to closed position to cut oil thesupply of fluid pressure to said annular fluid chamber and meansresponsive to the pressure in said suction chamber for controlling saidfluid means.

OTTO A. LABUS. EMIL T. NEUBAUER. ROBERT G. MINER.

References Cited in the file Of this patent UNITED STATES PATENTS NumberName Date 2,028,577 Kuhl Apr. 28, 1936 2,274,337 Bitter Feb. 24, 19422,304,999 Gonzalez Dec. 15, 1942 2,329,931 Neeson Sept. 21, 19432,387,117 Buehler, Jr Oct. 16, 1945 FOREIGN PATENTS Number Country Date461,838 Great Britain 193'1

